Aerial Application of Trichogramma to Control Codling Moth in Walnuts

Codling moth, Cydia pomonella, is a major exotic pest of walnuts, apples and pears in California. Current control practices, using the application of conventional pesticides, are costly, toxic and declining in effectivenss. Of additional concern in California is that many walnut orchards are planted along major river systems in former riparian zones where growers are or will be required to use environmentally safe management practices. Trichogramma, a minute parasitic wasp completing its development within eggs of host moths, effectively meets this requirement. Present application methods used in walnuts are not optimal. Aerial application of Trichogramma parasitoids to the orchard canopy will increase the wasp's success in controlling codling moth, improve crop yields and substantially reduce pesticide applications. This project proposes to: 1) evaluate existing aerial equipment, modifying or redesigning as necessary, to apply Trichogramma parasitoids to the orchard; 2) evaluate carrier materials and survivability of parasitoids when applied with each unit; 3) evaluate lateral distribution of parasitoids applied by air; and 4) evaluate the addition of glue at application to hold the parasitoids in the canopy, increasing the wasp's successful breeding and subsequent parasitism of codling moth eggs.